Diffusion of $CH_{4(g)}$ and $O_{2(g)}$ occurs under similar conditions,then the ratio of their rates of diffusion is

Which of the following is true for the gaseous state?

$50 \ mL$ of each gas $A$ and gas $B$ takes $150$ and $200$ seconds respectively for effusing through a pinhole under similar conditions. If the molecular mass of gas $B$ is $36$,the molecular mass of gas $A$ will be:

$A$ mixture of $N_2$ and $Ar$ gases in a cylinder contains $7 \ g$ of $N_2$ and $8 \ g$ of $Ar$. If the total pressure of the mixture of gases in the cylinder is $27 \ bar$,the partial pressure of $N_2$ is $......... \ bar$.
[Use atomic masses (in $g \ mol^{-1}$) : $N=14, Ar=40$]

$A$ container consists of a mixture of $28 \ g \ N_2$,$8 \ g \ He$,and $40 \ g \ Ne$ at $25^{\circ} C$. If the total pressure exerted by the gaseous mixture is $20 \ bar$,what is the partial pressure exerted by $N_2$ (in $bar$)?

Name two phenomena that can be explained on the basis of surface tension.